Carboplatin dosing based on measurement of renal function--experience at the Peter MacCallum Cancer Institute

Multicenter Phase 1b/2a Clinical Trial of Radioprotectant BIO 300 Oral Suspension for Patients With Non-Small Cell Lung Cancer Receiving Concurrent Chemoradiotherapy

PURPOSE

Radiation therapy is part of the standard treatment regimen for non-small cell lung cancer (NSCLC). Although radiation therapy is an effective tool to manage NSCLC, it can be associated with significant dose-limiting toxicities. These toxicities can lead to treatment interruption or early termination and worsening clinical outcomes in addition to reductions in patient quality of life. Based on preclinical efficacy for radioprotection of normal tissues, we evaluated the clinical utility of BIO 300 Oral Suspension (BIO 300; synthetic genistein nanosuspension) in patients with NSCLC.

METHODS AND MATERIALS

In this multicenter, open-label, single-arm, ascending dose phase 1b/2a study, patients were enrolled with newly diagnosed stage II-IV NSCLC planned for 60 to 70/1.8-2.0 Gy radiation therapy and concurrent weekly paclitaxel/carboplatin. Oral BIO 300 (cohort 1, 500 mg/d; cohort 2, 1000 mg/d; cohort 3, 1500 mg/d) was self-administered once daily starting 2 to 7 days before initiating concurrent chemoradiotherapy and continued until the end of radiation therapy. The primary endpoint was acute dose-limiting toxicities attributable to BIO 300. Secondary outcomes included pharmacokinetics, pharmacodynamics, overall toxicity profile, quality of life, local response rate, and survival.

RESULTS

Twenty-one participants were enrolled. No dose-limiting toxicities were reported. BIO 300 dosing did not alter chemotherapy pharmacokinetics. Adverse events were not dose-dependent, and those attributable to BIO 300 (n = 11) were all mild to moderate in severity (grade 1, n = 9; grade 2, n = 2) and predominantly gastrointestinal (n = 7). A dose-dependent decrease in serum transforming growth factor β1 levels was observed across cohorts. Based on safety analysis, the maximum tolerated dose of BIO 300 was not met. Patient-reported quality of life and weight were largely stable throughout the study period. No patient had progression as their best overall response, and a 65% tumor response rate was achieved (20% complete response rate).

CONCLUSIONS

The low toxicity rates, along with the pharmacodynamic results and tumor response rates, support further investigation of BIO 300 as an effective radioprotector.

Optimized Dosing: The Next Step in Precision Medicine in Non-Small-Cell Lung Cancer

In oncology, and especially in the treatment of non-small-cell lung cancer (NSCLC), dose optimization is often a neglected part of precision medicine. Many drugs are still being administered in "one dose fits all" regimens or based on parameters that are often only minor determinants for systemic exposure. These dosing approaches often introduce additional pharmacokinetic variability and do not add to treatment outcomes. Fortunately, pharmacological knowledge is increasing, providing valuable information regarding the potential of, for example, therapeutic drug monitoring. This article focuses on the evidence for the most promising and easily implemented optimized dosing approaches for the small-molecule inhibitors, chemotherapeutic agents, and monoclonal antibodies as treatment options currently approved for NSCLC. Despite limitations such as investigations having been conducted in oncological diseases other than NSCLC or the retrospective origin of many analyses, an alternative dosing regimen could be beneficial for treatment outcomes, prescriber convenience, or financial burden on healthcare systems. This review of the literature provides recommendations on the implementation of dose optimization and advice regarding promising strategies that deserve further research in NSCLC.

Accurate determination of glomerular filtration rate in adults for carboplatin dosing: Moving beyond Cockcroft and Gault

OBJECTIVE

Carboplatin is a cytotoxic chemotherapy drug developed in the 1980s which is still widely used today across various tumour types. Despite its common application, there remains a significant controversy and practice variation on its unique method of dosing by area under the curve (AUC). One potential reason for this variability stems from the reliance of using an estimated glomerular filtration rate (eGFR) as an extrapolation of the measured GFR (mGFR) which the commonly used Calvert equation was originally validated for. This review takes a novel and collaborative nephro-oncology approach to highlight the historical evolution of carboplatin dosing, methods for estimating GFR and its relative performance in the application of carboplatin dosing for adult patients.

DATA SOURCES

We reviewed all pertinent publications comparing carboplatin AUC-based dosing in adult patients based on the various methods of GFR measurements or estimations in order to provide a comprehensive description of each method's advantages and risks.

DATA SUMMARY AND CONCLUSIONS

The Cockcroft-Gault equation has been widely studied but newer eGFR equations, such as the CKD-Epidemiology Collaboration (CKD-EPI) or Janowitz-Williams equation have outperformed the Cockcroft-Gault in recent studies.

Glomerular filtration rate: comparison of simultaneous plasma clearance of 99mTc-DTPA and 51Cr-EDTA revisited

The issue of whether ^99mTc-DTPA can replace ⁵¹Cr-EDTA for measurement of plasma clearance as a surrogate for glomerular filtration rate (GFR) is of great relevance to daily clinical practice. Prompted by the shortage of ⁵¹Cr-EDTA we conducted a head-to-head comparison in patients attending our department for GFR determination. The two tracers (3.7 MBq of ⁵¹Cr-EDTA and 8 MBq of ^99mTc-DTPA) were administered intravenously immediately after each other, and the standard number of blood samples were drawn. Fifty-four patients were enrolled. In 51 of these, single-sample measurement was performed with the following results: GFR_EDTA was 84.6 ± 23.3 mL/min, GFR_DTPA was 84.2 ± 24.7 mL/min. The mean difference was 0.4 ± 2.8 mL/min, p = 0.32, and results based on the two tracers were highly correlated (r = 0.995). GFR_DTPA exceeded GFR_EDTA at high GFR values (difference < 0 at GFR_EDTA >91.4 mL/min) and vice versa (difference > 0 at GFR_EDTA < 91.4 mL/min). However, differences fell within few GFR units that most often will have no clinical consequence. We therefore conclude that ^99mTc-DTPA can replace ⁵¹Cr-EDTA for single-sample determination of GFR in a clinical setting.

Analysis of carboplatin dosing in patients with a glomerular filtration rate greater than 125 mL/min: To cap or not to cap? A retrospective analysis and review

The use of the Calvert formula to calculate carboplatin doses allows clinicians to achieve the appropriate carboplatin area under the concentration (AUC) curve. Thrombocytopenia is the dose limiting toxicity of carboplatin and optimizing AUC minimizes the risk of thrombocytopenia. Carboplatin clearance directly correlates with glomerular filtration rate (GFR) and, therefore, an accurate estimation of the renal function is needed. The Calvert formula was designed using the GFR measured by 51Cr-EDTA; however, many clinicians substitute estimated creatinine clearance (CrCl) as calculated by the Cockcroft–Gault (C–G) equation. The potential for overestimating AUC occurs when clinicians substitute actual weight in obese patients or use a low serum creatinine when calculating C–G estimated CrCl. In 2010, the National Cancer Institute recommended the GFR value within the Calvert formula should not exceed 125 mL/min, thereby capping the carboplatin dose. However, there are studies demonstrating that certain patients’ actual GFR values do exceed 125 mL/min. Therefore, capping the carboplatin dose in these patients may lead to underestimating the carboplatin AUC. A single-center, retrospective study was performed to evaluate the change in platelet count pre- and post-carboplatin exposure in patients with C–G estimated CrCl greater than 125 mL/min receiving capped versus uncapped carboplatin doses. A review of carboplatin dosing strategies is also presented. This study indicated there was a larger mean difference in pre- and post-platelet count in patients receiving uncapped carboplatin compared to patients receiving capped carboplatin with no differences in toxicities. Dose capping this patient population will likely lead to a lower AUC rather than the intended AUC target, which could ultimately lead to substandard outcomes.

Update on Cancer Treatment in Exotics

Treatment options for animals with cancer are rapidly expanding, including in exotic animal medicine. Limited information is available about treatment effects in exotic pet species beyond individual case reports. Most cancer treatment protocols in exotic animals are extrapolated from those described in humans, dogs, and cats. This review provides an update on cancer treatment in exotic animal species. The Exotic Species Cancer Research Alliance accumulates clinical cases in a central location with standardized clinical information, with resources to help clinicians find and enter their cases for the collective good of exotic clinicians and their patients.

Genome-wide association study of paclitaxel and carboplatin disposition in women with epithelial ovarian cancer

Identifying single nucleotide polymorphisms (SNPs) that influence chemotherapy disposition may help to personalize cancer treatment and limit toxicity. Genome-wide approaches are unbiased, compared with candidate gene studies, but usually require large cohorts. As most chemotherapy is given cyclically multiple blood sampling is required to adequately define drug disposition, limiting patient recruitment. We found that carboplatin and paclitaxel disposition are stable phenotypes in ovarian cancer patients and tested a genome-wide association study (GWAS) design to identify SNPs associated with chemotherapy disposition. We found highly significant SNPs in ABCC2, a known carboplatin transporter, associated with carboplatin clearance (asymptotic P = 5.2 × 10⁶, empirical P = 1.4 × 10⁻⁵), indicating biological plausibility. We also identified novel SNPs associated with paclitaxel disposition, including rs17130142 with genome-wide significance (asymptotic P = 2.0 × 10⁻⁹, empirical P = 1.3 × 10⁻⁷). Although requiring further validation, our work demonstrated that GWAS of chemotherapeutic drug disposition can be effective, even in relatively small cohorts, and can be adopted in drug development and treatment programs.

Verifying Carboplatin Dose Calculations in Adult Patients with the Calvert and Modified Calvert Formulas

The increasing complexity of cancer chemotherapy makes it mandatory that pharmacists be familiar with these highly toxic agents. This column reviews various issues related to the preparation, dispensing, and administration of cancer chemotherapy, both commercially available and investigational.

Gallium-68 EDTA PET/CT for Renal Imaging

Nuclear medicine renal imaging provides important functional data to assist in the diagnosis and management of patients with a variety of renal disorders. Physiologically stable metal chelates like ethylenediaminetetraacetic acid (EDTA) and diethylenetriamine penta-acetate (DTPA) are excreted by glomerular filtration and have been radiolabelled with a variety of isotopes for imaging glomerular filtration and quantitative assessment of glomerular filtration rate. Gallium-68 ((68)Ga) EDTA PET usage predates Technetium-99m ((99m)Tc) renal imaging, but virtually disappeared with the widespread adoption of gamma camera technology that was not optimal for imaging positron decay. There is now a reemergence of interest in (68)Ga owing to the greater availability of PET technology and use of (68)Ga to label other radiotracers. (68)Ga EDTA can be used a substitute for (99m)Tc DTPA for wide variety of clinical indications. A key advantage of PET for renal imaging over conventional scintigraphy is 3-dimensional dynamic imaging, which is particularly helpful in patients with complex anatomy in whom planar imaging may be nondiagnostic or difficult to interpret owing to overlying structures containing radioactive urine that cannot be differentiated. Other advantages include accurate and absolute (rather than relative) camera-based quantification, superior spatial and temporal resolution and integrated multislice CT providing anatomical correlation. Furthermore, the (68)Ga generator enables on-demand production at low cost, with no additional patient radiation exposure compared with conventional scintigraphy. Over the past decade, we have employed (68)Ga EDTA PET/CT primarily to answer difficult clinical questions in patients in whom other modalities have failed, particularly when it was envisaged that dynamic 3D imaging would be of assistance. We have also used it as a substitute for (99m)Tc DTPA if unavailable owing to supply issues, and have additionally examined the role of (68)Ga EDTA PET/CT for measuring glomerular filtration rate and split renal function.

Comparison between Two-sample Method with 99mTc-diethylenetriaminepentaacetic acid, Gates' Method and Estimated Glomerular Filtration Rate Values by Formula Based Methods in Healthy Kidney Donor Population

Purpose of the Study:

Glomerular filtration rate (GFR) is the most important parameter for the assessment of renal function. GFR by plasma sampling technique is considered accurate in the selection of donors for renal transplantation. Estimated GFR (eGFR) calculations using Gates’ method and Modification of Diet in Renal Disease (MDRD) and Cockcroft–Gault (CG) equations are simple methods but have not been validated in the Indian population. Hence, we aimed to assess the correlation between these three techniques.

Materials and Methods:

The plasma sampling technique was done using two samples at 60 and 180 min after injection of 1 mCi (37MBq) ^99mTc-diethylenetriaminepentaacetic acid (^99mTc-DTPA) in 66 healthy donors. Age, sex, height, weight, and plasma creatinine were recorded. Normalized GFR (nGFR) by two-sample method and eGFR (for Gates’, MDRD, and CG) values were calculated using formulae.

Results:

There were 14 male and 52 female donors. Mean age was 46.56 ± 12.88 years (24–69 years). Mean height was 153.74 ± 8.35 cm, whereas mean weight was 56.97 ± 11.88 kg. Mean nGFR value was 80.4 for two-sample method while mean eGFR value for Gates’, CG, and MDRD were 83.3, 89.36, and 97.47 ml/min/1.73 m² (eligibility value at our institution = 70), respectively. While the correlation between nGFR and eGFR CG and MDRD was weak moderate (correlation coefficient = 0.5), nGFR and eGFR Gates’ had a moderate correlation (0.686). Mean total bias for eGFR Gates’, CG, and MDRD were 2.87, 8.93, and 17.0, respectively. P₃₀ of eGFR Gates’, CG and MDRD were 60.6%, 57.6%, and 62.1%, respectively.

Conclusions:

Due to the large variability in eGFR Gates’, CG and MDRD, nGFR estimation using the plasma sampling technique with ^99mTc-DTPA appears necessary while screening healthy donors for renal transplantation.

Dose-banding of carboplatin: rationale and proposed banding scheme

Background. In dose-banding (DB) prescribed doses of cancer chemotherapy are fitted to doseranges or ‘bands’ and standard doses for each band are provided using a selection of pre-filled infusions or syringes, either singly or in combination. DB is used for several drugs where dose is based on body surface area. No DB-scheme has been reported for carboplatin, which, in clinical practice, is routinely dosed according to renal function.

Study objective. To assess the rationale for DB of carboplatin with regards to factors that influence dosing accuracy, develop a DB scheme, and discuss its potential use and limitations.

Methods. Prospective evaluations of carboplatin area under the plasma concentration – time curve (AUC) following application of the Calvert-formula were identified by a literature search. A relevant carboplatin dose range for construction of a DB-scheme with Calvert-formula based doses was obtained from published glomerular filtration rate distributions for patients receiving carboplatin.

Results. A DB-scheme was developed for individually calculated carboplatin doses of 358–1232 mg, with 35 mg increments between each standard dose and a maximum deviation of 4.7% from prescribed dose. The proposed DB-scheme covers the GFR-ranges 47–221 mL/min and 26–151 mL/min for patients receiving doses based on the target AUCs of 5 and 7 mg/mL/min, respectively.

Conclusion. There is a strong scientific rationale to support DB of carboplatin. The proposed banding scheme could introduce benefits to patients and healthcare staff but, as with other DB schemes, should be validated with prospective clinical and pharmacokinetic studies to confirm safety and efficacy.

68Ga-EDTA PET/CT imaging and plasma clearance for glomerular filtration rate quantification: comparison to conventional 51Cr-EDTA

Glomerular filtration rate (GFR) can accurately be determined using (51)Cr-ethylenediaminetetraacetic acid (EDTA) plasma clearance counting but is time-consuming and requires technical skills and equipment not always available in imaging departments. (68)Ga-EDTA can be readily available using an onsite generator, and PET/CT enables both imaging of renal function and accurate camera-based quantitation of clearance of activity from blood and its appearance in the urine. This study aimed to assess agreement between (68)Ga-EDTA GFR ((68)Ga-GFR) and (51)Cr-EDTA GFR ((51)Cr-GFR), using serial plasma sampling and PET imaging.

METHODS

(68)Ga-EDTA and (51)Cr-EDTA were injected concurrently in 31 patients. Dynamic PET/CT encompassing the kidneys was acquired for 10 min followed by 3 sequential 3-min multibed step acquisitions from kidneys to bladder. PET quantification was performed using renal activity at 1-2 min (PETinitial), renal excretion at 2-10 min (PETearly), and, subsequently, urinary excretion into the collecting system and bladder (PETlate). Plasma sampling at 2, 3, and 4 h was performed, with (68)Ga followed by (51)Cr counting after positron decay. The level of agreement for GFR determination was calculated using a Bland-Altman plot and Pearson correlation coefficient (PCC).

RESULTS

(51)Cr-GFR ranged from 10 to 220 mL/min (mean, 85 mL/min). There was good agreement between (68)Ga-GFR and (51)Cr-GFR using serial plasma sampling, with a Bland-Altman bias of -14 ± 20 mL/min and a PCC of 0.94 (95% confidence interval, 0.88-0.97). Of the 3 methods used for camera-based quantification, the strongest correlation was for plasma sampling-derived GFR with PETlate (PCC of 0.90; 95% confidence interval, 0.80-0.95).

CONCLUSION

(68)Ga-GFR agreed well with (51)Cr-GFR for estimation of GFR using serial plasma counting. PET dynamic imaging provides a method to estimate GFR without plasma sampling, with the additional advantage of enabling renal imaging in a single study. Additional validation in a larger cohort is warranted to further assess utility.

Very high GFR in cancer patients undergoing chemotherapy: prevalence, carboplatin dosing patterns and chemotherapy toxicity

AIM

Carboplatin dosing depends on accurate glomerular filtration rate (GFR) estimation. There is a lack of clinical agreement about carboplatin dosing when the GFR measurement is very high (>110 mL/min).

METHODS

A retrospective audit of pre-chemotherapy 99m technetium (Tc) diethylenetriamene pentaacetate (DTPA) radionuclide GFR estimations and patients' chart review were performed from January 2006 to May 2009. The primary objective was to determine the prevalence of patients with a high GFR and the incidence of myelotoxicity in this group.

RESULTS

Overall 18 of 148 treated patients (14%) measured GFR >110mL/min. The GFR values of six of the 18 patients were capped for dose calculation. In eight patients a measured GFR corrected for body surface area was used and in four the actual measured GFR was used for dose calculation. In total, 63 cycles of chemotherapy were delivered. Grade III or IV myelotoxicity accounted for 37% (15/41) of all myelotoxicities. Neutropenia accounted for almost 39% of all myelotoxicities (16/41). Two patients (11%) were hospitalized due to febrile neutropenia. Eight patients (40%) had dose reduction and four (20%) had treatment delays due to myelotoxicity. The frequency of myelotoxicity was high irrespective of the GFR used (corrected or uncorrected) in calculating the chemotherapy dose.

CONCLUSION

High values of GFR, by 99mTc DTPA radionuclide measurement, are a common finding in pre-chemotherapy patients irrespective of age. Carboplatin dosing patterns in this group of patients vary among treating oncologists and a standardized approach is needed.

Evaluation of glomerular filtration rate estimation by Cockcroft-Gault, Jelliffe, Wright and Modification of Diet in Renal Disease (MDRD) formulae in oncology patients

BACKGROUND

The aim was to evaluate the accuracy of Cockcroft-Gault, Jelliffe, Wright and Modification of Diet in Renal Disease (MDRD) formulae as a substitute for the gold standard measure of glomerular filtration rate (GFR) using chromium 51 EDTA.

PATIENTS AND METHODS

Retrospective analysis of GFR measurements in oncology patients from a University Teaching Hospital over 3 years was carried out. Bias and precision of estimates of GFR were compared with measured GFR.

RESULTS

Six hundred and sixty patients with measured GFR (median 90 ml/min, range 23-179 ml/min) were identified. Cockcroft-Gault produced the smallest bias (median percentage error -1.4%) and highest precision (median absolute percentage error 14.0%) and was the most accurate for carboplatin dosing. For patients>30% over their ideal body weight (IBW), using IBW+30% in the Cockcroft-Gault formula was more precise than using actual body weight or IBW. The Wright formula was most accurate for patients aged 70+years and patients with a body mass index (BMI)≥30 but overestimated GFR when GFR<50 ml/min.

CONCLUSIONS

When measured GFR is unavailable, we advise estimating GFR using the Cockcroft-Gault formula and using IBW+30% for patients weighing>30% over their IBW. If the GFR is ≥50 ml/min and the patient is >70 years and/or BMI≥30, the Wright formula gives the best estimate of GFR.

Safety creatinine clearance level for platinum chemotherapy in lung cancer patients

The present study was carried out to evaluate whether measured-creatinine clearance (measured-CrCl) and Cockcroft and Gault-CrCl (CG-CrCl) are capable of appropriately detecting a decline in renal function in lung cancer patients, including elderly patients, and to clarify a CrCl level with which to discriminate between patients with or without renal impairment. The measured-CrCl prior and subsequent to platinum-based chemotherapy of lung cancer patients was retrospectively analyzed. Measured-CrCl and CG-CrCl were evaluated prior and subsequent to platinum-based chemotherapy for lung cancer. Measured-CrCl and CG-CrCl in 59 lung cancer patients including 25 patients aged ≥65 years were retrospectively analyzed. In patients treated with carboplatin-based chemotherapy, measured-CrCl was indicative of a decline in renal function, whereas CG-CrCl was not. The optimal measured-CrCl level was <60 ml/min post-pretreatment and >90 ml/min at pre-treatment. In cases with pre-treatment measured-CrCl levels of >90 ml/min, favorable renal function is necessary in order to carry out platinum-based chemotherapy in lung cancer patients, including the elderly.

Evaluation of creatinine-based formulas in dosing adjustment of cancer drugs other than carboplatin

Background. Glomerular filtration rate (GFR) is often used to determine initial dosing of renally excreted cancer drugs. GFR can be calculated using the Cockcroft-Gault (CG) or the modified diet in renal diseases (MDRD) study formulas, both of which are based on serum creatinine levels. The MDRD formula is more accurate in noncancer patients, does not require patient weight, and is reported automatically by all laboratories in British Columbia, Canada. We previously showed that the CG and MDRD formulas have similar accuracy for carboplatin dosing in patients with gynecological malignancies. We now examine dosing of all renally excreted cancer drugs in the general cancer population. Since this setting does not include routine measurement of GFR, we report the concordance of estimates of GFR derived from the CG and MDRD formulas.

Methods. Patient data were collected retrospectively at the BC Cancer Agency. The primary outcome was the proportion of patients who would have received a different initial dose due to difference in the GFR. Each patient’s dose was determined from dose adjustment tables stated in specific treatment protocols. The secondary outcome was concordance of the GFR derived from CG and MDRD, using the method of Bland and Altman. A difference of >30% was assumed to be clinically significant because this difference would usually lead to dose adjustment based on reclassification of renal function.

Results. A total of 313 patients were evaluated, with 40% male. The median age was 56 years, weight 67.5 kg, height 166 cm, and serum creatinine 74 µmol/L (0.84 mg/dL). The median GFR derived from the CG and MDRD formulas were 86.8 mL/min (mean 91 mL/min, SD ± 30 mL/min) and 87.6 mL/min (mean 88 mL/min, SD ± 26 mL/min), respectively. A total of 8.6% (27/313) of patients would have received a different dose due to difference in the GFR; of these, 67% (18/27) would have received a higher dose. A difference of >30% in GFR was found in 17.9% (56/313) of patients.

Conclusions. There is good concordance of the GFR derived from the CG and MDRD formulas for most cancer patients, with less than 10% of patients expected to receive a different initial dose of chemotherapy. The MDRD formula may be a reasonable alternative to the CG formula for dosing of cancer drugs which are renally excreted or nephrotoxic. J Oncol Pharm Practice (2010) 16: 113—119.

Phase I pharmacokinetic and pharmacodynamic study of Carboplatin and topotecan administered intravenously every 28 days to patients with malignant solid tumors

PURPOSE

Preclinical studies have shown that the combination of topotecan and carboplatin is synergistic. To evaluate the schedule dependency of this interaction, the following phase I trial was designed to determine the safety and maximum tolerated dose (MTD), pharmacokinetics, and pharmacodynamics of carboplatin and topotecan in patients with malignant solid tumors.

EXPERIMENTAL DESIGN

In part 1, patients received carboplatin on day 1 and topotecan on days 1, 2, and 3 (C-->T schedule). In part 2, topotecan was administered on days 1, 2, and 3, followed by carboplatin on day 3 (T-->C schedule). Pharmacokinetics were determined in plasma and DNA topoisomerase I catalytic activity and Pt-DNA adducts in WBC and tumor tissue.

RESULTS

Forty-one patients were included. Dose-limiting toxicities during the C-->T schedule were grade 4 thrombocytopenia and febrile neutropenia (MTD: carboplatin target area under the free carboplatin plasma concentration versus time curve, 4 min mg/mL; topotecan, 0.5 mg/m(2)/d). Dose-limiting toxicities during the T-->C schedule included grade 4 neutropenia, thrombocytopenia, neutropenic fever, and grade 4 nausea and vomiting (MTD: carboplatin target area under the free carboplatin plasma concentration versus time curve, 6 min mg/mL; topotecan, 0.9 mg/m(2)/d). One complete response and five partial responses were observed. The clearance of and exposure to carboplatin and topotecan did not depend on the sequence of drug administration. No schedule-dependent effects were seen in Pt-DNA levels and DNA topoisomerase I catalytic activity in WBC and tumor tissue. However, myelotoxicity was clearly more evident in the C-->T schedule.

CONCLUSION

The T-->C schedule was better tolerated because both hematologic and nonhematologic toxicities were milder. Other pharmacodynamic factors than the ones investigated must explain the schedule-dependent differences in toxicities.

Dose calculation of anticancer drugs

BACKGROUND

Anticancer drugs are characterized by a narrow therapeutic window and significant inter-patient variability in therapeutic and toxic effects. Current body surface area (BSA)-based dosing fails to standardize systemic anticancer drug exposure and other alternative dosing strategies also have their limitations. Just as important as the initial dose selection is the subsequent dose revision to ensure the dose is correct.

OBJECTIVE

To provide an insight into the different dose individualization and dose adjustment methods, their feasibility and applicability in daily oncology practice and to suggest a practical framework for dose calculation and a basis for future research.

METHODS

Review of relevant literature related to dose calculation of anticancer drugs.

RESULTS

Strategies using clinical parameters, genotype and phenotype markers, and therapeutic drug monitoring all have potential and each has a role for specific drugs. However, no one method is a practical dose calculation strategy for many or all drugs.

CONCLUSION

Given that BSA-dosing leads to significant underdosing it is not reasonable to use this as the sole method of dose calculation. Because of wide disparity in individual patient characteristics and elimination mechanisms, we are unlikely to find the 'Holy Grail' of a single individualized dosing strategy for every patient and anticancer drug in the near future. We propose a pragmatic, although invalidated system for initial dose calculation using dose clusters and structured subsequent dose revision based on treatment-related toxicities and therapeutic drug monitoring. These models need to be tested in clinical trials.

Comparison of glomerular filtration rate measurements with the two plasma sample and single plasma sample, gamma camera Gates, creatinine clearance, and prediction equation methods in potential kidney donors with normal renal function

OBJECTIVE

To compare measured glomerular filtration rate (GFR) by single plasma sample methods (SPSMs), gamma camera Gates, 24-h endogenous creatinine clearance, and prediction equations (Cockcroft-Gault and modification of renal disease (MDRD)) with the two plasma sample method (TPSM) considered as the reference in potential kidney donors with normal renal function.

METHODS

One hundred and fifteen subjects (50 male, 65 female; mean age 41.9+/-12.2 years) with normal renal function were prospectively included in this study. GFR was calculated by TPSM (120-min and 240-min samples) and SPSM (180-min sample).

RESULTS

While there was strong statistically significant correlation between the TPSM and all SPSMs, low correlation was found in Gates, creatinine clearance, Cockcroft-Gault and MDRD. In all SPSMs, 95% limits of agreements were consistent with each other and within clinically acceptable limits. The lowest bias, median absolute difference, mean percentage error, and the best precision were found for Christensen and Groth's method as modified by Watson (CGmW).

CONCLUSIONS

Among the SPSMs, CGmW can reflect GFR more accurately than the other methods. Neither the gamma camera Gates method nor the creatinine clearance method nor the prediction equations (Cockcroft-Gault and MDRD) could calculate GFR accurately. All these techniques could result in mistakes in the management of potential kidney donors.

Chemotherapy Dosing Part II: Alternative Approaches and Future Prospects

This overview follows on from part I, which described the current practices used in chemotherapy dosing and the paucity of scientific evidence to support them. In part II, alternative approaches are discussed, both in terms of scientific rationale and practical application. These include therapeutic drug monitoring, the use of pharmacokinetic-pharmacodynamic relationships, flat-fixed dosing, Bayesian modelling and dose banding.

Flat Dosing of Carboplatin Is Justified in Adult Patients with Normal Renal Function

PURPOSE

The Calvert formula is a widely applied algorithm for the a priori dosing of carboplatin based on patients glomerular filtration rate (GFR) as accurately measured using the 51Cr-EDTA clearance. Substitution of the GFR in this formula by an estimate of creatinine clearance or GFR as calculated by formulae using serum creatinine (SCR; Cockcroft-Gault, Jelliffe, and Wright) is, however, routine clinical practice in many hospitals. The goal of this study was to validate this practice retrospectively in a large heterogeneous adult patient population.

EXPERIMENTAL DESIGN

Concentration-time data of ultrafilterable platinum of 178 patients (280 courses, 3,119 samples) with different types of cancer receiving carboplatin-based chemotherapy in conventional and high doses were available. Data were described with a linear two-compartment population pharmacokinetic model. Relations between SCR-based formulae for estimating renal function and carboplatin clearance were investigated.

RESULTS

None of the tested SCR-based estimates of renal function were relevantly related to the pharmacokinetic variables of carboplatin. Neither SCR (median, 51; range, 18-124 micromol/L) nor the estimated GFR using the three different formulae was related to carboplatin clearance.

CONCLUSIONS

Our data do not support the application of modifications of the Calvert formula by estimating GFR from SCR in the a priori dosing of carboplatin in patients with relatively normal renal function (creatinine clearance, >50 mL/min). For targeted carboplatin exposures, the original Calvert formula, measuring GFR using the 51Cr-EDTA clearance, remains the method of choice. Alternatively, in patients with normal renal function, a flat dose based on the mean population carboplatin clearance should be administered.

Relationship of Hepatic Functional Imaging to Irinotecan Pharmacokinetics and Genetic Parameters of Drug Elimination

Purpose

The marked variability of irinotecan (Ir) clearance warrants individualized dosing based on hepatic drug handling. The aims of this trial were to identify parameters from functional hepatic nuclear imaging (HNI) that correlate with (1) Ir pharmacology, and (2) single-nucleotide polymorphisms (SNPs) for the ABCB1 (P-glycoprotein) and UGT-1A1 genes, known to influence Ir handling.

Methods

Patients underwent genotyping for ABCB1 SNPs and UTUGT-1A1*28 carriage and HNI with 99mTc-DIDA (acetanilidoiminodiacetic acid)/ 99mTc-DISIDA (disofenin) and MIBI (99mTc-sestamibi) scans, probes for biliary transport proteins ABCC1 and -2, and ABCB1 function. HNI data were analyzed by noncompartmental and deconvolutional analysis to provide hepatic extraction and biliary excretion parameters. Patients received Ir, fluorouracil, and folinic acid using a weekly ×2, every-3-weeks schedule. Plasma was taken for Ir and SN-38 analysis on day 1, cycle 1.

Results

Of the 21 patients accrued, Ir pharmacokinetics data were obtained from 16 patients. 99mTc-DIDA/DISIDA percent retention at 1 hour (1-hour RET) correlated to baseline serum bilirubin (P = .008). Both 99mTc-DIDA/DISIDA and MIBI 1-hour RET correlated with SN-38 area under the curve (AUC; P < .01). On multiple regression analysis, SN-38 AUC = −215 + 18.68 × bilirubin + 4.27 × MIBI 1-hour RET (P = .009, R2 = 44.2%). HNI parameters did not correlate with Ir toxicity or UGT1A1*28 carriage. MIBI excretion was prolonged in patients with the ABCB1 exon 26 TT variant allele relative to wild-type (P = .015).

Conclusion

Functional imaging of hepatic uptake and excretory pathways may have potential to predict Ir pharmacokinetics. Evaluation of a larger cohort as well as polymorphisms in other biliary transporters and UGT1A1 alleles is warranted.

Difference of carboplatin clearance estimated by the Cockroft–Gault, Jelliffe, Modified-Jelliffe, Wright or Chatelut formula

OBJECTIVE

Although the Calvert formula is the standard method to calculate the dose of carboplatin, there is no consensus how to determine the glomerular filtration rate (GFR) without using [51Cr]-ethylenediamine tetraacetic acid (51Cr-EDTA). Creatinine clearance (Ccr), calculated using the Cockroft-Gault, Jelliffe, Modified-Jelliffe or Wright formulae, has been used as a substitute for the GFR. In addition to these four formulae, the Chatelut formula has been proposed as a way to calculate carboplatin clearance. Among these formulae, Jelliffe formula does not include body surface area (BSA) or body weight to adjust the body size and thus may have greater bias than the other four formulae in estimating carboplatin clearance. The purpose of this study is to evaluate if these five formulae could equally estimate the carboplatin clearance.

METHODS

: Carboplatin clearance was estimated in 253 patients with gynecologic cancer who received carboplatin-based chemotherapy between January 1996 and August 2004. Ccr was estimated using the Cockroft-Gault, Jelliffe, Modified-Jelliffe or Wright formulae. Carboplatin clearance was also calculated directly by using the Chatelut formula. The five estimations of carboplatin clearance were compared with each other using the post-hoc Wilcoxon signed rank test. The median percent error (MPE) and the median absolute percent error (MAPE) were evaluated by comparing carboplatin clearance. The relationships between BSA and ratios of estimated carboplatin clearance (Jelliffe/Cockroft-Gault, Jelliffe/Modified-Jelliffe, Jelliffe/Wright, Jelliffe/Chatelut) were evaluated by using simple regression.

RESULTS

: The estimated carboplatin clearances were: Cockroft-Gault formula, 109.8 +/- 28.4; Jelliffe formula, 128.5 +/- 28.2; Modified-Jelliffe formula, 110.8 +/- 25.7; Wright formula, 112.2 +/- 24.3; Chatelut formula, 114.1 +/- 33.0. A statistically significant difference was observed between carboplatin clearance calculated using Jelliffe formula and that given by each of the other four formulae. Comparing the results of the Cockroft-Gault formula with the Jellife, Modified-Jelliffe, Wright and Chatelut formulae yielded MPEs of +19%, +2%, +3% and +3% and MAPEs of 27%, 5%, 6% and 6%, respectively. There was a significant correlation between BSA and ratio of estimated carboplatin clearance (Jelliffe/Cockroft-Gault, Jelliffe/Modified-Jelliffe, Jelliffe/Wright, Jelliffe/Chatelut), with Pearson correlation coefficients of 0.928, 0.847, 0.965 and 0.839 respectively. As the BSA of patient became smaller, the differences between the carboplatin clearance calculated by the Jelliffe formula from other four formulas became larger.

CONCLUSIONS

: Estimates of carboplatin clearance calculated by the Jelliffe formula tend to have greater positive bias compared to the other four formulae, particularly when the BSA of the patient is small. In order to conduct collaborative international studies, it may be necessary to standardize the formula used to estimate carboplatin clearance to perform international collaboration studies.

Accurate measurement of individual glomerular filtration rate in cancer patients: an ongoing challenge

A narrow therapeutic index is a characteristic feature of cytotoxic agents. Some of these agents are almost entirely eliminated renally in unchanged active form. As a consequence, assessment of the individual glomerular filtration rate (GFR) may help to predict the pharmacokinetic behaviour of cytotoxic agents in plasma more precisely. In addition, GFR-adapted individualization of cancer chemotherapy may have an enormous impact on the severity of side effects. Several methods are available to determine GFR or creatinine clearance (CrCl). GFR-measurement based on experimental methods with radiolabelled isotopes, contrast media or inulin helps to reflect the real situation very closely. In addition, 24-h urine collection is a convenient and feasible method to measure creatinine clearance. Finally, several mathematical equations exist to estimate GFR or CrCl based on serum creatinine and other parameters. Only a few of these equations have been developed in oncologic patients. However, some of these equations are routinely used in clinical practice, because they allow a rapid estimation of GFR. Based on the fact that clinically relevant differences have been assessed between calculated values and the real situation, mathematical calculation of GFR or CrCl does not seem to be appropriate to assess individual renal function precisely enough over a broad range of individual GFR or CrCl. Whether the measurement of low-molecular-weight proteins, such as cystatin C and ss-trace protein, may help to reflect the real situation more precisely is a matter of controversial debate.

Postoperative chemoradiotherapy for high-risk head-and-neck squamous cell carcinoma

PURPOSE

To describe the use of postoperative concurrent chemoradiotherapy, with either weekly cisplatin or carboplatin, for high-risk head-and-neck squamous cell carcinoma (HNSCC) in a single institutional setting.

METHODS AND MATERIALS

Between July 1999 and January 2003, 47 patients were treated with postoperative chemoradiotherapy.

RESULTS

Of the 47 patients, 41 (87%) had Stage III-IV disease. The predominant primary site was the oral cavity in 24 patients (51%), 27 had nodal disease with extracapsular extension, and 26 had positive or close mucosal margins (<5 mm). Ten patients had undergone resection of recurrent disease after previous surgery. Twenty-seven (57%) were treated with cisplatin, and the remaining patients received carboplatin because of contraindications to cisplatin. The median radiotherapy dose was 60 Gy (range, 50-66 Gy). Of the 47 patients, 45 (96%) completed at least four of the six planned doses of chemotherapy and 45 (96%) completed the planned course of radiotherapy. Nineteen patients (40%) had confluent mucositis, eight (17%) had Grade 3-4 hematologic toxicity, and four (9%) had febrile neutropenia. No treatment-related deaths occurred. The estimated 2-year locoregional control, progression-free survival, and overall survival rate was 73%, 56%, and 62%, respectively. Excluding the 10 patients with recurrence after previous surgery, the locoregional control, progression-free survival, and overall survival rate was 81%, 64%, and 71%, respectively. Five cases of Grade 3-4 late treatment-related sequelae developed.

CONCLUSION

Treatment with postoperative concurrent weekly cisplatin or carboplatin and radiotherapy was reasonably well tolerated. Acute and late toxicity was acceptable. The overall results achieved are comparable with the preliminary results of recent randomized trials. Patients treated after resection of recurrent disease (after previous surgery alone) fared worse than those treated at the initial resection.

Assessing outcomes of cancer care: Lessons to be learned from a retrospective review of the management of small cell lung cancer at the Cancer Therapy Centre, Liverpool Hospital, January 1996-July 2000

The purpose of the present paper was to review the outcomes of care of small cell lung cancer (SCLC) at one Sydney teaching hospital. A retrospective cohort study was carried out of patients with SCLC seen between January 1996 and July 2000. The main outcomes were relapse-free and overall survival. Secondary outcomes of interest were the uniformity of staging investigations, initial treatment, use of prophylactic cranial irradiation (PCI), patterns of relapse and treatment received following relapse. One hundred and three patients with SCLC were treated at the Liverpool Hospital Cancer Therapy Centre during this period. There were 58 men (56%) and 45 women (44%). Forty-two patients (41%) had limited stage disease (LD) and 61 (59%) had extensive stage disease (ED). There was considerable variation in staging investigations. There was little variation in systemic treatment of SCLC. Only 32 of 42 patients with limited stage SCLC were candidates for thoracic radiotherapy and only seven patients received PCI. Median relapse-free survival was 11.2 months (95% confidence interval (CI): 7.7-14.8) for patients with LD and 6 months (95%CI: 4.4-7.5) for ED. Median overall survival was 15.1 months (95%CI: 11-19.1) for patients with LD and 8.9 months (95%CI: 7.5-10.2) for ED. Some health outcomes similar to that reported in clinical trials can be achieved in clinical practice. Measuring health outcomes is an important process of maintaining quality of care.

A randomized cross-over trial to determine the effect of Cremophor EL on the pharmacodynamics and pharmacokinetics of carboplatin chemotherapy

PURPOSE

Paclitaxel, when combined with carboplatin, exhibits a platelet-sparing effect. Paclitaxel is formulated in Cremophor EL (CrEL), which has been shown in preclinical models to reduce haematological toxicity from radiotherapy and chemotherapy. We sought to determine the effect of a 3-h infusion of 20 ml/m2 (equivalent to 175 mg/m2 paclitaxel) CrEL on myelosuppression following carboplatin chemotherapy, and the effect of CrEL on carboplatin pharmacokinetics.

METHODS

A total of 16 patients with locally advanced or metastatic cancer were randomized to receive either CrEL or saline over 3 h prior to carboplatin (area under the curve, AUC, 5-7). Each patient was subsequently crossed over to the other treatment. Blood samples were collected at selected time-points for estimation of platinum AUC and 24-h platinum levels. Full blood counts were obtained three times per week.

RESULTS

Of the 16 patients randomized, 15 were evaluable. Myelosuppression was measured by percentage fall at nadir and nadir levels. No significant differences were obtained when comparing CrEL and saline with respect to the above end-points after adjusting for multiple testing. There was no evidence to indicate that CrEL altered the pharmacokinetics of carboplatin.

CONCLUSION

CrEL at this dose and schedule does not appear to be a major contributory factor to the platelet-sparing effect of paclitaxel when combined with carboplatin, nor does it alter the pharmacokinetics of carboplatin.

Rounding of low serum creatinine levels and consequent impact on accuracy of bedside estimates of renal function in cancer patients

To compare glomerular filtration rate measured by technetium-99m ([Tc^99m]) DTPA clearance with estimated creatinine clearance (CrCl) (Cockcroft and Gault (C&G) method) in patients with serum creatinine (Scr) levels <0.06 mmol l⁻¹, and determine the effect of rounding serum creatinine to 0.06 mmol l⁻¹. Patients with serum creatinine values <0.06 mmol l⁻¹ at the time of [Tc^99m] clearance determination were identified. Creatinine clearance was calculated by the C&G method using both actual and rounded Scr values. A total of 419 adults had GFR measured by technetium-99m diethyl triamine penta-acetic acid ([Tc^99m] DTPA) clearance. Out of this group, 26 patients had a serum creatinine value <0.06 mmol l⁻¹. The C&G estimates of renal function using actual serum creatinine resulted in an overall overestimation of 12.9% when compared to [Tc^99m] DTPA clearance. When the value of serum creatinine was rounded to 0.06 mmol l⁻¹, the formula underestimated renal function by −7.0%. Analysis of estimated creatinine clearance for different levels of renal function showed significant differences to [Tc^99m] DTPA clearance. Rounding up of serum creatinine to 0.06 mmol l⁻¹ improved the predictive ability of the C&G method for the patients with [Tc^99m] DTPA clearance ⩽100 ml min⁻¹, but worsened the effect in those >100 ml min⁻¹. This work indicates that when bedside estimates of renal function are calculated using the C&G formula actual Scr should be used first to estimate CrCl. If the resultant CrCl is ⩽100 ml min⁻¹, then the Scr should be rounded up to 0.06 mmol l⁻¹ and CrCl recalculated. Further assessment of this approach is warranted in a larger cohort of patients.

Toxicity of platinum compounds

Since the introduction of platinum-based combination chemotherapy, particularly cisplatin, the outcome of the treatment of many solid tumours has changed. The leading platinum compounds in cancer chemotherapy are cisplatin, carboplatin and oxaliplatin. They share some structural similarities; however, there are marked differences between them in therapeutic use, pharmacokinetics and adverse effects profiles [1-4]. Compared to cisplatin, carboplatin has inferior efficacy in germ-cell tumour, head and neck cancer and bladder and oesophageal carcinoma, whereas both drugs seem to have comparable efficacy in advanced non-small cell and small cell lung cancer as well as ovarian cancer [5-7]. Oxaliplatin belongs to the group of diaminocyclohexane platinum compounds. It is the first platinum-based drug that has marked efficacy in colorectal cancer when given in combination with 5-fluorouracil and folinic acid [8,9]. Other platinum compounds such as oral JM216, ZD0473, BBR3464 and SPI-77, which is a pegylated liposomal formulation of cisplatin, are still under investigation [10-13], whereas nedaplatin has been approved in Japan for the treatment of non-small cell lung cancer and other solid tumours. This review focuses on cisplatin, carboplatin and oxaliplatin.

A comparison of bedside renal function estimates and measured glomerular filtration rate (Tc99mDTPA clearance) in cancer patients

BACKGROUND

The aim of this study was to compare measured glomerular filtration rate (GFR) with estimates of GFR derived from the population pharmacokinetic methods of Martin and Wright, and the creatinine clearance (CrCl) estimates of Cockcroft and Gault, and Jelliffe.

PATIENTS AND METHODS

GFR was determined by technetium-99m diethyl triamine penta-acetic acid (Tc99DTPA) clearance in adult cancer patients. Height, actual body weight and serum creatinine were measured, and GFR and CrCl estimates calculated.

RESULTS

One hundred and twenty-two patients were included. The mean measured GFR was 87 ml/min (range 30-174 ml/min). The mean bias (mean percentage error) was 2, 1, -10 and -17%, and the mean precision (mean absolute percentage error) was 18, 19, 21 and 23% for the Wright, Martin, Cockcroft and Gault, and Jelliffe formulas, respectively. The Martin formula significantly underestimates GFR for females (mean bias -10%) and overestimates GFR for males (mean bias 8%) (P <0.001 for bias of males versus females). The Wright and Martin formulas significantly overestimate GFR <50 ml/min (mean bias 39 and 30%; P = 0.03 and 0.05, respectively) and all formulas underestimate GFR >100 ml/min (mean bias -18, -16, -24 and -32% for Wright, Martin, Cockcroft and Gault, and Jelliffe formulas, respectively; P <0.001).

CONCLUSIONS

All the assessed estimates for renal function were found to have significant limitations.

Carboplatin dosing: gender bias and inaccurate estimates of glomerular filtration rate

The aim was to compare doses of carboplatin calculated using the Calvert formula and Chatelut formula and also to compare doses calculated using Calvert formula, modified with non-isotopic estimation of GFR, using the Cockcroft and Gault formula or the Jelliffe formula. For formulae comparison, doses were calculated to target an AUC of 7 mg/ml x min. When compared with the dose derived from the Calvert formula, the doses calculated in 122 adult cancer patients using the Chatelut formula were significantly higher for males and significantly lower for females. There was a statistically significant difference between the dose per kg calculated for males and females (P<0.0001). The mean percentage difference in dose calculated with substituted measures of renal function with the Cockcroft and Gault formula and Jelliffe formula was -8% (standard deviation (S.D.) 17%) and -14% (S.D. 16%), respectively. Further prospective evaluation of the Chatelut formula is required before it can be recommended for routine clinical application.

Repetitive high-dose topotecan, carboplatin, and paclitaxel with peripheral blood progenitor cell support in previously untreated ovarian cancer: results of a Phase I study

OBJECTIVE

In view of the significant activity of topotecan in ovarian cancer with dose-limiting toxicity (DLT) of myelosuppression, we evaluated the addition of topotecan to carboplatin and paclitaxel with peripheral blood progenitor cell (PBPC) support.

METHODS

Patients with previously untreated stage IIIC or IV ovarian cancer with macroscopic residual disease following primary debulking surgery were eligible. Patients received two cycles of carboplatin AUC = 5 and 175 mg/m(2) of paclitaxel with collection of PBPCs after the second cycle. Patients subsequently received three cycles of high-dose therapy (HDT) with topotecan on a daily x5 schedule, paclitaxel (250 mg/m(2) over 24 h), and carboplatin (AUC = 12-16).

RESULTS

Nineteen patients with a median age of 49 years (range 21-63) were enrolled and topotecan was escalated in 6 patient cohorts up to a dose of 4.5 mg/m(2)/day. Fifty-two of the planned 57 treatment cycles were delivered with no treatment-related deaths. Neutrophil and platelet recovery was rapid and the interval between HDT was 28 days. Febrile neutropenia occurred following 57% of all HDT cycles. DLTs of mucositis and diarrhea were observed at topotecan (4.5 mg/m(2)/day), paclitaxel (250 mg/m(2)) and carboplatin (AUC = 12). The protocol was subsequently modified to administer topotecan (2.5 mg/m(2)/day) with carboplatin (AUC = 16); however, 2 patients developed grade 4 diarrhea (1 with grade 3 mucositis and 1 with grade 4 mucositis). The clinical CR rate was 73% (14/19) with an overall clinical response rate of 95% (18/19). Of the 14 patients with a CCR, 13 of these underwent a second-look laparotomy with 8 (61%) achieving a pathological CR. With a median follow-up of 28 months (range 11-40 months), the median PFS is 36 months and OS has not been reached.

CONCLUSION

When combined with carboplatin (AUC = 12) and paclitaxel (250 mg/m(2)), the recommended topotecan dose is 3.5 mg/m(2)/day for 5 days. This outpatient HDT regimen combines three of the most active drugs in ovarian cancer with acceptable toxicity and promising activity.

Carboplatin and vinorelbine in untreated locally advanced and metastatic non-small cell lung cancer

The aim of this study was to assess the activity and toxicity of carboplatin/vinorelbine combination chemotherapy in unresectable locally advanced and metastatic non-small cell lung cancer. Between April 1997 and June 1999 30 patients (22 M, eight F, median age 62) received treatment with carboplatin AUC 6 on day 1, and vinorelbine 25mg/m(2) on days 1, 8 and 15. Treatment was given every 28 days for six cycles unless progressive disease occurred. Twenty-three patients (77%) had stage IV disease, and seven (23%) stage IIIB. Ninety-three percent were WHO performance status 0-1. Twenty-three patients were fully assessable. Nine patients achieved partial responses (9/23, 39%) for an overall objective response rate of 9/30 (30%; 95% CI 15-49%). The median duration of response was 2.75 months (range 1-13 months). The median progression-free survival was 2 months and the median survival 5.25 months. The actuarial 1-year survival was 20%. The median number of cycles completed was two (range 1-6). Day 15 vinorelbine was administered in only 18% of cycles. The main toxicity was myelosuppression. WHO grade III/IV neutropenia was experienced in 50% of patients, however, there were only three episodes of febrile neutropenia. Eight patients required blood transfusion and one developed grade III thrombocytopenia. Treatment was ceased in one patient because of grade IV autonomic neuropathy. No patient had significant nausea and vomiting. There were no treatment-related deaths. These results indicate that carboplatin/vinorelbine is well tolerated and has similar activity to cisplatin/vinorelbine in patients with unresectable non-small cell lung cancer, however, the median survival was considerably shorter.

Estimation of glomerular filtration rate in cancer patients

The frequent need to obtain an estimate of renal function in cancer patients, not least for targeting carboplatin dose, has led to a number of approaches to estimate glomerular filtration rate (GFR). This study aimed to develop a simple and reliable method to estimate GFR using readily-available patient characteristics. Data from 62 patients with estimates of 51Cr-EDTA clearance were analysed to determine the most appropriate formula relating this method of measuring GFR to patient characteristics. The population pharmacokinetics of 51Cr-EDTA were analysed using NONMEM to evaluate the influence of each covariate. The formulae derived were then validated using a further 38 patients and compared with those obtained using existing formulae. 51Cr-EDTA clearance (GFR) was positively related to Dubois surface area, negatively related to age, and inversely related to serum creatinine (SCr). Females had lower 51Cr-EDTA clearance than males. The enzymatic method of SCr assay gave more reliable results than the Jaffe colorimetric method. A measure of creatine kinase significantly improved the estimation of GFR. The new formula produced estimates of GFR which were less biased (Mean Prediction Error = -3%) and more precise (Mean Absolute Prediction Error = 12%) than Cockcroft and Gault (-8% and 16%) or Jelliffe (-15% and 19%) estimates. The formulae developed here can be used to provide reliable estimates of GFR, particularly in regard to targeted dosing of carboplatin.

A comparison of methods of calculation for estimating carboplatin AUC with a retrospective pharmacokinetic-pharmacodynamic analysis in patients with advanced non-small cell lung cancer. European Lung Cancer Working Party

We retrospectively analysed the data obtained in a large randomised trial performed in 505 eligible patients with advanced non-small cell lung cancer. Its purpose had been to compare a combination of carboplatin (200 mg/m2) and cisplatin (60 mg/m2) with or without the addition of ifosfamide. The present retrospective analysis assessed two ways of dosing carboplatin: according to body surface area (mg/m2) or to the estimated targeted area under the concentration versus time curve (AUC). Two different methods were used in the latter calculation: the Calvert formula using the Cockroft approximation to evaluate the glomerular filtration rate and the Chatelut equation. There was an excellent linear correlation between them. With the Chatelut method, the calculated administered AUC were lower. Whichever method was used, carboplatin AUC was not significantly associated with antitumour response rate nor patient survival. A statistically significant increase in haematological toxicity, mainly thrombopenia, was observed with an increase in the AUC. This effect was observed whatever AUC variable was considered, i.e. total dosage at course one, total dosage during the first three chemotherapy courses or dose intensity during the first three courses. The effect remained highly significant after adjustment for treatment arm. We conclude that for a moderate carboplatin dose in non-small cell lung cancer, the therapeutic index could be improved if dosage is calculated according to the AUC.

A phase II trial of carboplatin and etoposide for relapsed or metastatic carcinoma of the cervix

This study reports the results of a phase II trial of carboplatin 100 mg/m2 combined with etoposide 120 mg/m2 each given for 3 consecutive days every 28 days in women with recurrent or metastatic carcinoma of the cervix. Seventeen eligible patients were treated between August, 1990 and May, 1993. In the 16 evaluable patients, there were 2 complete responses, and no partial responses with an overall objective response rate of 12.5% (95% confidence interval 1.6%-38%). The main toxicities of this regimen related to myelosuppression and emesis. The combination of carboplatin and etoposide did not achieve either a better response rate or a substantially improved toxicity profile than is seen with single agent cisplatin.